<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        function Person(name,sex) {
            this.name = name;
            this.sex = sex;

        }
        Person.prototype.extend = function(obj){
            for(var k in obj) {
                this[k]=obj[k];

            }
        }
        function Student(num) {
            this.num = num;
        }
        Student.prototype = new Person('jack','男');
        var stu = new Student('001');
        console.log(stu);
    </script>
</body>
</html>